Electrovibration-based haptics may refer to the use of an electrostatic force to provide one or more sensations to a user as, for example, the user's finger slides across the surface of a touch-sensitive screen. In an example, the user slides her finger across a surface of a touch-sensitive screen that employs electrodes, and an electric potential is applied to the electrodes. The quality of the grounding path between the source of the electric potential and the user significantly affects the quality and intensity of the haptic experience. It is therefore difficult to provide a consistent haptic experience to the user unless the system has an explicit ground connection with the user (e.g., there is a consistent grounding path to the user at all times).
A conventional solution to provide a consistent haptic experience to the user is to use wrist straps to ground the user. It is inconvenient, however, to require the user to wear additional equipment that is connected to the device. Another conventional technique is to require another finger or part of the user's hand to touch the device. This, however, may force the device to be held in a specific way, and again is inconvenient. Another conventional technique is to have no ground connection. This works if the signal is strong enough; however, this may still result in an inconsistent haptic experience for the user.
The user experience may also be different depending on factors that affect the grounding path including, for example, how the user is standing, whether the user is connected directly to the device, and whether the user is in contact with someone else.